A production line is a set of sequential operations established in a factory whereby materials are advanced through processing stations providing a refining process to produce an end-product.
Automated production lines exist where workers and/or fully automated production equipment, e.g. including robots, are arranged along a conveyer which brings material forward. Traditionally, the conveyer is moved regularly or continuously, in such a manner that the processing time of each sequential operation is taken into account.
Particularly, with respect to processing of a web, it is typically required to synchronize movement of the conveyer with operation time at each processing station, and it is typically challenging to optimise all processing stations for equal processing time and to avoid tension in the web.
A difference in operation time will typically lead to idling of processing stations of the less time consuming processes since the movement of the conveyor is adapted to allow the most time consuming process to finalize.
To balance differences in operation time, several processing stations may jointly accomplish the most time consuming processes. In case of malfunction in one of the processing stations, bottlenecks may, however, develop, and it is typically difficult, if not impossible, to completely balance the differences between the processes. As a result, very long conveyors are sometimes applied to provide sufficient space of identical processing stations and for establishing sufficient material to avoid tension in the web etc.
U.S. Pat. No. 1,769,546 discloses a conveyer system where the speed can be changed along the conveyer, and the belt comprises two parallel endless chains made of links. Between each chain, a work-supporting bar carries a rubber belt. A cam-plate causes cross-rods to move apart whereby the material will be stretched. The stretching is possible due to friction with the material.
U.S. Pat. No. 2,487,354 discloses a plurality of article supporting members in the form of circular cup like members which are connected to and moved by a chain made from a plurality of chain links. The guide-way comprises a narrow single file portion and a wider double file portion. In the wider portion, the chain and the article supports will be shifted into a zig-zag relationship until they assume the double file relationship. The sprocket wheel which drives the chain may thus drive at a constant speed while the supporting members are moved forward along the guide-way at full speed in the single file portion and at near half-speed in the double file portion.
There remains a need for a device which is capable of conveying or processing long webs, e.g. of a fragile material.